The radical kozato shows a hill. 阝 and is always on the left side of a kanji. (Please note that rather similar radical oozato⻏ is always on the right sight of the kanji and means village.)
云 has the meaning "fog" only in Chinese. This original meaning is still visible in: cloud 雲. In Japanese it has the meaning to say/speak. For "fog" itself the character: 霧 (MU, kiri) is used.
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and corner フ) and: fog/mist 云 (cf. cloud 雲)
